For future runs: I like getting a room at the Transit Hotel. There's a bed, a shower, and you can leave all your stuff in the room while you roam the airport. Advance reservations are essential. If they say they don't have room, ask to be put on the waiting list. I've done this twice and cleared the waiting list both times.

For what it's worth, it was after 9/11 when security let me onto the concourse without a boarding pass. They did it twice, actually; the other time I had to go out from the Transit Hotel and deal with a luggage snafu. (SQ wouldn't transfer our luggage from a late SQ flight to the morning UA NRT flight. Ended up using the Left Luggage desk in the basement for the seven hours between flights.)

Are you planning to use one of the premium lounges for a shower before your return trip? At least you'll have an hour or so on the concourse before you depart.